膜下滴灌条件下水氮供应对棉花根系及叶片衰老特性的调节

【目的】探讨膜下滴灌条件下，水氮运筹对棉花产量形成期根系及叶片衰老特性、产量和水分利用效率的调节效应，为调控滴灌棉花早衰和提高棉花产量提供依据。【方法】在土柱栽培条件下，采用膜下滴灌技术控制水氮的供应量及分配比例，共设置4个水分、2个氮肥运筹共8个处理，研究水氮供应方式对膜下滴灌棉花根系生长、根系活力、根系及叶片保护性酶活性、产量和水分利用效率的影响。【结果】与其它水氮供应方式相比，播前灌条件下盛花期前限量滴灌后恢复充分滴灌配合重施花铃肥的水氮供应方式显著促进了棉花深层根系生长、增强了根系活力，根系及叶片SOD活性较高、MDA含量较低，延缓了植株衰老进程，提高光合产物向生殖器官分配的比例、增加铃重，从而获得了较高的产量和水分利用效率。【结论】播前灌溉条件下，适当减少盛花前水氮供应、增加生育中后期水氮的分配比例是提高膜下滴灌棉花产量和水分利用效率的有效水氮运筹方式。

Effect of Irrigation and Nitrogen Application Regimes on Senescent Characters of Roots and Leaves in Cotton with Under-Mulch-Drip Irrigation

【Objective】 To investigate the effect of irrigation and nitrogen application regimes on the senescent characters of roots and leaves, yield and water use efficiency (WUE), experiments were conducted using cotton with under-mulch-drip irrigation at yield forming stages. Providing evidence for regulating cotton senescence and improving yield will be of great significance to the cotton production.【Method】All the cotton plants were planted in soil columns under the same conditions but with different amounts of water and nitrogen supply at different growth stages, and different distribution proportions, before inseminating. There were eight treatments of four amounts of water and two amounts of nitrogen used to research the effect of water and nitrogen application regime on root growth, root vigor, the activity of protective enzyme in roots and leaves, yield and WUE of cotton.【Result】The optimum water and nitrogen application regime that irrigated before insemination and limited irrigation before full flowering stage, followed by adequate recovery irrigation along with fertilization again at flowering and boll stage was the best. This treatment promoted root growth in deeper soil layers, strengthened root vigor, increased superoxide dismutase (SOD) activity in roots and leaves, and decreased malondialdehyde (MDA) content so that the senescence processes were delayed. Furthermore, it increased distribution from photosynthetic production to production in reproductive organs and increased boll weight. Consequently, a comparatively high yield and WUE were gained in this treatment.【Conclusion】The most efficient water and nitrogen application regime is that decrease water and nitrogen supply before full flowering stage, but increase distribution proportion of water and nitrogen at the middle and late growth stages. This can delay early senescence of cotton, promote distribution from photosynthetic production to reproductive organ production, increase cotton yield with under-mulch-drip irrigation, and increase the WUE.